1. Field of Invention
This invention relates to apparatus which provides for the automatic assembly of semiconductor devices such as an integrated circuit within a ceramic package, and more particularly to apparatus which provides a precise temperature cycle for parts being assembled.
2. Description of Prior Art
In the manufacture of semiconductor devices such as an integrated circuit an assembly procedure is required whereby protective covers must be assembled to a mechanical base which has the integrated circuit mounted thereon. Due to the miniaturization of these parts a logical method of assembling the mechanical parts leads to a process whereby heat is applied and sealing material strategically positioned on the parts is caused to melt and then rapidly solidify after being adhered to two or more mating surfaces.
Such methods involve the application of heat via conduction, convection or radiation; or any combination thereof. Most often utilized is a combination of radiation and convective heat transfer because of the problems associated with handling the production parts.
Prior art apparatus utilized to hermetically seal ceramic encapsulated packages were almost completely manual in operation. Production pieces were manually loaded on a handling fixture and loaded into a heated oven or furnace for a prescribed period of time. At the end of the heated cycle a cooling operation was directed to lower the temperature of the handling fixture containing the finished production pieces. This method of cooling is relatively slow and inefficient since the handling fixtures are relatively massive as contrasted to the small size of the semiconductor parts.
Recent emphasis has been placed on the development of methods and apparatus for accurately controlling process parameters where the application of heat is utilized as a means to seal production packages. Reliability studies indicate that the method of heat application for sealing purposes is an important factor in determining the strength and hermeticity of the seal.
The process of conductive heat transfer which is utilized in the instant invention is more effective since the parts to be assembled encounter a uniform heat flux within a precise temperature cycle. An improvement remaining to be made with conductive heat transfer utilized in the instant invention would be to eliminate the air film between the heated source and the part to be assembled.